Process and apparatus for refrigeration with liquefied fuel gas



April 25, 1933. 1,905,971

PROCESS AND APPARATUS FOR REFRIGERATION WITH LIQUEFIED FUEL GAS D. W.DAVISSON ET AL Filed July 28, 1931 2 Sheets-Sheet 1 :Delos W. DaviasonFerdinand G.We\ke Inventor's April' 25, 1933.

D. W. DAVISSON ET AL PROCESS ANP APPARATUS FOR REFRIGERATION WITHLIQUEFIED FUEL GAS Filed July 28, 1931 2 Sheets-Sheet 2 :DelosWDuvissong Ferdinand G .Welke BgTheir' Afiornel Patented Apr. 25, 1933UNITED STATES DELOS W. DAVISSON AND FERDHTAND'G..WELKE, 01' SANFRANCISCO,

PATENT OFFICE CALIFORNIA,

ASSIGNORS TO SHELL DEVELOPMENT COMPANY, 01 SAN FRANCISCO, CALIFORNIA,

A CORPORATION OF DELAWARE Application filed July 28,

This invention relates to a dual system wherein a direct expansion typecooling and.

refrigerating system is operated in conjunction with a fuel gasconsuming unit, and is more particularly concerned with a processwherein the cooling refrigerating medium is combustedwith a gas, afterit has'passed through the refrigerating system.

The objects and advantages of this improvement will 'be so clearlyapparent. to those skilled in the industry, asincidental to thefollowing disclosure, that it would serve no useful purpose to furtherenlarge upon the same initially. With these prefacing remarks,therefore, reference now will be immediately had to the accompanying.drawings, generally illustrating at least one practical embodiment of anovel systematic com- .bination of means for carryin forth the steps ofthe method involved, a though not essentially the only apparatusfor-doing so. Of these drawings:

a Fig. 1 illustrates a general flow diagram of the disclosed arrangementof the refrigcrating system.

Figs. 2 and 3 are plan and side elevation views, respectively, of theimproved refrigera-ting system installed on a truck.

In the drawings, wherein like characters of reference designatecorresponding parts throughout the several views, storage tank 1 is incommunication with a heat exchanger 4 .by means of'conduit2. Portion 3of a set of expansion coils 7 is arranged in heat exchange relationshipwith conduit 2, and the other portion 6 of coils 7, externally locatedof the cooling or refrigerating compartment 17 is arranged in 4,constituting 12 b ng the fluid surrounding the outside of coil 6 1n theheat exchanger 4 into coils 6 in the general direction offlow, asindicated on the drawings. A high pressure regulaparstypf the said heatexchanger. Pipes 11 and tor 5 is interposed between lines 11 and 12 andserves to maintain a predetermined pressure on the system at aparticular operating temperature. A pressure gauge 13 may be stationedbefore 5 and communicate with line 11 so as to indicate the prevailingpressure in the system up to that point. Expan- 1931. Serial at.553,524.

' line 15fa s to a predetermined value, which is lower than thepressurein line 14 and may be less than atmospheric. A suitable pressure gauge16 may be located in line 14. If desired, a pressure relief valve 10 maybe adjusted in line 14 so as to reduce or mini mizeithe pressureexisting therein, if it rises above a predetermined point.

Preparatory to starting. operations, the liquefied, normally gaseousfuel is stored in the high pressure section of the system, i. e., instorage .tank 1, line 2, the jacket of heat exchanger 4 and line 11extending to the high pressure regulator 5. The fuel under a pressure,and at the temperature at which it is maintained in the liquid state,flows through 2 in heat exchange relationship with the expanded exitfluid from expansion coils 7 in the last section 3 thereof, which ispositioned externally. of the refrigerating compartment 17, as in Figs.2 and 3, although, if desired, section 3 and line 2 may be positionedinside of refrigerating compartment 17 thus constituting a part ofcooling coils 7. The liquid fuel flows from 2 in a cooled state to heatexchanger 4, where it is further cooled, and passes by means of line 11through high pressureregulator 5 where the pressure in the system isstepped down to a predetermined one, normally one about a few poundsabove atmospheric pressure. The fuel is still a liquid at this reducedpressure due to the corresponding lowering of its temperature by meansof the heat water will solidify or freeze on the outside of coil 6 inheat exchanger 4 due to the low a temperature prevailing. therein, andcan subsequently be readily removed by stopping the flow momentarily anddefrosting in the usual manner, using drain valve 9 to remove water fromthe system.

The cooled fluid flowing through 12 and 6 takes up heat in the heatexchan er 4 and is vaporized in the expansion coils located in thecooling or refrigerating compartment 17,

75 utilized to cool the liquid entering at relatively high temperatureand pressure into the system. The exit gas in 14 is controlled by lowpressure regulator 8 which is adapted to permit flow of the same to acombustion or ower device, when the pressure in line 15 comes lower thana predetermined one. W ere low pressure regulator 8 not to operate, or apressure tend to build up in line 14, pressure relief valve 10 serves tovent such increased pressure to the atmosphere, or to any desiredapparatus; for example, it may also communicate with the sameordiflerent combustion or power devices.

For illustrative purposes only, reference will be had to the executionof our process with a preferred fuel, although it is to be understoodthat our invention is not to be restricted thereto, as it is capable ofuse with substantially any liquefied normally. gaseous fuel or mixturesof the same, particularly with hydrocarbon fuel.

A refrigerating system of the type described hereto, using liquefiedbutane as refrigerant, is installed on a truck, the motor of said vtruckbeing operated by combusting the exit gaseous butane from aforesaidsystem. I

The storage tank 1 containing liquefied butane at 75 F. under a.relative pressure of about 125' lbs/sq. in. is properly connected to thesystem and its stop valve opened. If

the relative pressure in coils 6 and 7 were less than 2 lbs./s in.gauge, the regulator will admit some o l the compressed butane intothese coils, until 2 lbs/sq. in. pressure is reached, when flow isautomatically cut ofi.

The low-pressure regulator 8 remains closed until suction is produced bythe motor in line 15. Starting the motor by-reciprocating pistons withinits cylinders causes partial vacuum in-the intake manifold, which is communicated through a'throttling device and line 15 to the regulator 8. Assoon as the subatmospheric pressure reaches the predetermined value of10 lbs/sq. in. absolute inline 15, the regulator 8 opens and releasespressure in coils 7 and'6, which in turn causes regulator 5 to open andrelease some of-the liquid butane into coils 6. The released fluidrapidly evaporates in coils 6 as result of into coils 7 where it iscompletely vaporizedwith the corresponding lowering of temperature incooling compartment 17. Passing further through a. heat exchanger 3 thegas is heated to atemperature of about 50-55 F When the motor is runningsteady for a period of time, a continuous and more or less .uniform flowof butane is maintained throughout the system, and general equilibriumconditions therein ensue. In this particular illustrative case, thepressure of 2 lbs/sq. in. gauge in expansion coils 7 determines thetemperature \of the fluid in coils 6 as about F. which is the vaorization temperature of butane under 2 l s./sq. in. gauge pressure. Asthe result of taking up the heat in coils 7, the temperature of the gasreaching heat exchanger 3 is raised to about 25 F., and thereafter toabout -55 F., whereas the temperature of the liquid butane in coil 2 islowered from about F. to about 3540 F. and to about 20 F. afteradditional cooling in heat exchanger 4. It is noted that thetemperatures in heat exchanger 4 are sufliciently below the freezingpoint 'of water to effect its complete removal by the solidification ofthe same on the outside surface of coils 6; thus danger of freez ing theregulator 5 is eliminated. It is also noted that the gaseous butane usedas motor fuel is conveniently preheated to an elevated temperaturewhichis a very advantageous feature of this system.

The rate of fuel flow to the motor is con-.

trolled by a special throttling device not subject to thisspecification.

. The conditions after the motor has been stopped are substantially asfollows: both regulators, 5 and 8, close immediately after pressures onthe downstream side of each have risen to those originallypredetermined, namely,'2 lbs/sq. in. gauge pressure and 10 lbs/sq. in.absolute, respectively. As the closed section of the systembetweenregulators 5 and 8- contains some liquid butane in coils 6, the pressurewithin this section will rise until all of the liquid is evaporated, andthe temperature of the surroundings is reached. This ultimate pressure,if tending to be excessively high, is controlled by the relief valve'10. which could be set, for instance, for 40 lb./sq. in. gauge. Thislimiting pressure may never be reached, however, as the amount of liquidbutane in coils 6 is comparatively small and therefore insufiicient toproduce gas generating such a pressure in coils 7.

scription of the tice additional parts maybe Gondition's somewhatdifferent in details, but similar in general effect, can be attained bythe use of other hydrocarbons, ,such as either iso-butane, or butylenes,or propane,

I or propylene, etc., or mixtures thereof. The

I if pentane be present the boiling temperature in coils 6 and 7 wouldnot be sufliciently low to effect satisfactory refrigeration, althou hcooling effects could be produced. Besi es hydrocarbons, theirsubstitution products, or any other combustible gases, which could beliquefied within reasonable economic limits of pressure and the boilingpoint of which at atmospheric pressure is not substantially above F.,and preferably below, can be used in a practical application of thisinvention. o I

While the foregoing is only a general de-' main pieces of equipmentnecessary to carry out the'opcration of the system in its simplest form,in actual pracutilized such'as thermometers, valves, etc., or adifferent arrangement of cooling coils may be used as in the case ofutilizing the produced refrigerating effect for the purpose of coolingthe motor by means of another heat transmitting medium, such as water oroil. Various modifications may be deemed advisable for spe-' cific usesof the described refrigerating system; these uses may include, besidesinstallations on various types'of trucks, passenger busses or vehicles,where cooling and not refrigeration is desired, installations on boats,stationary units, in dining cars, in country homes and other structureswhere combustible gas may be used for-cooking, illamina-ting orpower-producing purposes, or, generally, whenever the low cost ofconstruction and maintenance of a refrigerating unit, ruggedness andcompactness of apparatus,

a and available use for a gaseous fuel are determining factors.

It will be obviolisitherefore, that various substitutions in thecombustible andror refrigerating material, as well as, modifications inthe arrangement of different membcrs of the system may be made in thepractical application of tlus invention, but such substitutions andmodifications are to be. con}; sidered as comprehended by the above disclosure and included within purview of the following claims.

We claim as our'invention: V v 1. A fuel utilizing system comprising: astorage vessel for fuel, an expansion unit supported in a refrigerationcompartment, one end of said unit being in communication with a storagevessel, a high pressure regulator interposed between said vessel andsaid expansion unit, acombustion device in communication with the otherend of the expansion unit and a low pressure regulator interposedbetween said expansion uni-t and'the combustion device whereby saidexpansion unit is maintainedunder super-atmospheric pressure.

2. Process of refrigerating comprising reducing the pressure on anormally gaseous fuel stored under high pressure, vaporizing said fuelunder-super-atmospheric pressure,

reducing the pressure on the gas produced and-. I

thereafter combusting all of said gas.

3. Process of refrigerating comprising reducing the pressure on apropane butane mixture stored under high pressure, vaporizing saidmixture under super-atmospheric pressure, reducing the pressure on thegas produced and thereafter combusting all of said as. g 4. Process ofoperating a refrigerating motor truck comprising reducing the pressureon a liquefied hydrocarbon gas stored under high pressure, vaporizingsaid liquefied hydrocarbon gas under super-atmospheric pressure,reducingthe pressure on the gas produced, thereafter operating theinternal combustion motor of said truck by said gas.

-5. Method of refrigerating a motor truck conli rising: expanding andvaporizing a norma fuel in a refrigerating coil while maintaining saidcoil under super-atmospheric pressure, withdrawing the gas evolved insaid coil and thereafter passing saidgas into the motor of said truck.

6. Process of operating a refrigerating niotor truck comprising:reducing the pressure on a propane-butane mixture stored under highpressure, vaporizing said mixture under super-atmosphericpressure,reducing the.

pressure on the gas produced, thereafter op-' pressure on the gasproduced, thereafter operating the internal combustion motor of saidtruck solely by means of said gas.

8. Process of operating a refrigerating motor truck comprising: reducingthe pressure on a liquefied hydrocarbon gas to about two pounds persquare inch, evaporating said lydroca'rbon in a coil under a pressure ofabout two pounds per square inch, then passing {:{he gas produced intothe motor of said truc 9. Process of operating a refrigerating motortruck comprisingzreducing the .pressure on a liquefied hydrocarbon gasfrom about one hundred and twenty five pounds per I I into the motor ofsaid truck.

square inch to about two pounds per square inch, evaporating saidhydrocarbon in a coil under a pressure of about two pounds per squareinch, then passing the gas produced 10. A refrigerating motor truckoperated by liquefied gas comprising: a high pressure liquefied gascontainer, a line connecting said container with the motor of saidtruck, a refrigerating coil in said line and a pressure regulatorconnected to said coil.

.11. A refrigerating motor truck operated by 1i uefie'd gas comprising:a high pressure lique ed gas container, a line connecting said containerwith a pressure regulator, a refrigerating coil attached to saidregulator, and a line from said refrigerating coil to the motor 4 ofsaid truck.

12. A refrigerating motor truck operated by liquefied gas comprising: ahigh pressure liquefied gas container, a line connecting said containerwith a pressure regulator, a refrigerating coil attached to saidpressure regulator, a line from said refrigerating coil to the motor ofsaid truck, and a second pressure regulator in said line to the motor.

In testimony whereof, we have hereunto set our hands.

DELOS W. DAVISSON. FERDINAND G. WELKE. 1

